ACTH release in pituitary cell cultures. Effect of neurogenic peptides and neurotransmitter substances on ACTH release induced by hypothalamic corticotropin releasing factor (CRF).

Abstract

The effects of various neurogenic peptides and neurotransmitter substances on the release of ACTH induced by hypothalamic corticotropin releasing factor (HY-CRF) were investigated using monolayer cultured anterior pituitary cells. Test substances were given in combination with 0.05-0.1 hypothalamic extract (HE)/ml, because HE evoked a significant ACTH release and a linear dose response relationship was demonstrated sequentially between 0.0165 HE/ml and 0.5 HE/ml. Relative high doses of lysine-vasopressin showed a slight additive effect on the release of ACTH induced by 0.1 HE/ml. Leu-enkephalin, dopamine, prostaglandin E1 and E2 slightly reduced the release of ACTH induced by HY-CRF, but the inhibitory effect of these substances were not dose-related. Other tested substances including luteinizing hormone releasing hormone, thyrotropin releasing hormone, somatostatin, melanocyte stimulating hormone release inhibiting factor, beta-endorphin, neurotensin, substance P, vasoactive intestinal polypeptide, angiotensin II, norepinephrine, serotonin, acetylcholine, histamine and gamma-amino butyric acid showed neither agonistic nor antagonistic effect on the release of ACTH induced by HY-CRF. These results indicate that the release of ACTH is controlled specifically by HY-CRF and corticosterone, and modified slightly by some other substances such as vasopressin and prostaglandins, and that the effect of most other neurogenic peptides and neurotransmitter substances is negligible or non-physiological at the pituitary level.

Effects of Lithium on the Hypothalamo-Pituitary-Adrenal Axis.

“…Although lithiuminduced ACTH release seemed to be very slight in monolayer cultured pituitary cells, it cannot be denied that lithium acts directly on the corticotrophs to release ACTH in vivo, as the cultured pituitary cells are sensitive to CRF and even vasopressin exercised a slight ACTH releasing activity in this system (Hashimoto et al, 1979).…”

Distribution and Characterization of Corticotropin-Releasing Factor and Arginine Vasopressin in Rat Hypothalamic Nuclei

“…CRF bioassay was performed with cultured rat anterior pitu itary cells as described previously [15]. Briefly, the rat anterior pituitaries were removed, dispersed with Hank's buffer containing collagenase and bovine serum albumin at 37 °C for 45 min.…”

Neuronal histamine and expression of corticotropin-releasing hormone, vasopressin and oxytocin in the hypothalamus: relative importance of H1 and H2 receptors

“…Furthermore, histaminergic neurons, which originate exclusively in the posterior hypothalamus (1), seem to be involved in the mediation of stressinduced release of these hormones (2). Since HA does not appear to stimulate ACTH/b-endorphin (3,4) or prolactin secretion (5,6) directly at the pituitary level, its action may be indirect via activation of hypothalamic neurons, which subsequently release hypophysiotropic factors which stimulate pituitary hormone secretion. Corticotropin-releasing hormone (CRH) as well as arginine-vasopressin (AVP) and oxytocin (OT) are involved in regulation of ACTH and b-endorphin (7,8) secretion, and AVP and OT are also involved in control of prolactin secretion (9).…”